In rail systems of the present invention, bins suspended from one track are electrically driven onto another track, and vice versa as needed. A bridge crane transfers bins from tracks at charging stations to tracks at unloading stations and returned, empty, alternately to charging stations. The tracks at the charging and unloading stations are known as "spur tracks." When the track carried by the bridge crane and the spur tracks are not aligned, the bin could be inadvertently driven off the end of the track onto the floor. Regulations require that a stop be engaged to block the bin from passing the end of an open track.